■http://anond.hatelabo.jp/20081026132547

FizzBuzz続き

Cにもlambdaがあればいいのに

#include <stdio.h>
#include <unistd.h>
#define FALSE 0
#define TRUE !FALSE

typedef struct state_t {
    int state;
    int num;
    int max;
    int outputted;
} state_t;

typedef struct fsm_t {
    state_t *(*func)(struct fsm_t *, state_t *);
    int divider;
    char *str;
} fsm_t;

static state_t *fizzbuzz(fsm_t *, state_t *);
static state_t *end_of_line(fsm_t *, state_t *);
static state_t *cond(fsm_t *, state_t *);
static state_t *succ(fsm_t *, state_t *);

static fsm_t fsm[] = {
    { fizzbuzz, 3, "Fizz" },
    { fizzbuzz, 5, "Buzz" },
    { end_of_line, 0, NULL },
    { cond, 0, NULL },
    { NULL, 0, NULL },
};

static state_t *fizzbuzz(fsm_t *fsm, state_t *cur) {
    if ((cur->num % fsm[cur->state].divider) == 0) {
        printf("%s", fsm[cur->state].str);
        cur->outputted = TRUE;
    }
    return succ(fsm, cur);
}

static state_t *end_of_line(fsm_t *fsm, state_t *cur) {
    if (!cur->outputted)
        printf("%d", cur->num);
    puts("");
    cur->outputted = FALSE;
    return succ(fsm, cur);
}

static state_t *cond(fsm_t *fsm, state_t *cur) {
    if (++cur->num > cur->max)
        return NULL;
    return succ(fsm, cur);
}

static state_t *succ(fsm_t *fsm, state_t *cur) {
    if (fsm[++cur->state].func == NULL)
        cur->state = 0;
    return cur;
}

int main(void) {
    state_t state = { 0, 1, 100, FALSE };
    state_t *cur = &state;

    while ((cur = (*fsm[cur->state].func)(fsm, cur)) != NULL)
        ;

    return 0;
}

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